# xoroshiro128+ random number generator

```Spotted this reddit post the other day:
```
```
... and it reminded me that I've been meaning for some time to follow up on the interesting RNG designs by Sebastiano Vigna and colleagues. Since I had a free moment, I thought I'd knock up a D port of the public-domain C reference code available here:
```http://xorshift.di.unimi.it/xoroshiro128plus.c

```
It's a first draft and obviously needs documentation, tests, etc. before I submit it to Phobos, but I thought I'd throw it out here if anyone wants to play with it and/or comment. I'll also try to follow up in the next days with an xorshift1024* implementation, which should be similarly straightforward.
```
Code follows -- enjoy! :-)

struct Xoroshiro128plus
{
public:
enum bool isUniformRandom = true;

/// Range primitives
enum bool empty = false;

/// ditto
ulong front() @property @safe const nothrow pure
{
return s[0] + s[1];
}

/// ditto
void popFront() @safe nothrow pure
{
immutable ulong s1 = s[1] ^ s[0];
s[0] = rotateLeft(s[0], 55) ^ s1 ^ (s1 << 14);
s[1] = rotateLeft(s1, 36);
}

void seed(ulong s0, ulong s1) @safe nothrow pure
in
{
// seeds are not both 0
assert(!(!s0 && !s1));
}
body
{
s[0] = s0;
s[1] = s1;
}

void seed(ulong[2] s01) @safe nothrow pure
in
{
// seeds are not both 0
assert(!(!s01[0] && !s01[1]));
}
body
{
s[] = s01[];
}

private:
ulong[2] s;

static ulong rotateLeft(ulong x, int k) @safe nothrow pure
in
{
assert(k <= 64);
}
body
{
return (x << k) | (x >> (64 - k));
}
}

```
• xoroshiro128+ random nu... Joseph Rushton Wakeling via Digitalmars-d-announce